RESUMEN
Commensal bacteria are crucial for maturation and function of the mucosal immune system. However, the mechanisms of these interactions are poorly understood. In addition, the role of the composition of the microbiota and the importance of individual species in this community in stimulating different types of immunity are major unanswered questions. We recently showed that the balance between two major effector T cell populations in the intestine, IL-17(+) Th17 cells and Foxp3(+) Tregs, requires signals from commensal bacteria and is dependent on the composition of the intestinal microbiota. Comparison of microbiota from Th17 cell-deficient and Th17 cell-sufficient mice identified segmented filamentous bacteria (SFB) as capable of specifically inducing Th17 cells in the gut. SFB represent the first example of a commensal species that can skew the mucosal effector T cell balance and thus affect the immune fitness of the individual.
Asunto(s)
Bacterias/inmunología , Inmunidad Mucosa/inmunología , Intestinos/inmunología , Intestinos/microbiología , Linfocitos T Reguladores/inmunología , Animales , Bacterias/ultraestructura , Interleucina-17/inmunología , Intestinos/ultraestructura , Ratones , Linfocitos T Reguladores/ultraestructuraRESUMEN
During fetal development, lymphoid tissue inducer cells (LTis) seed the developing lymph node and Peyer's patch anlagen and initiate the formation of both types of lymphoid organs. In the adult, a similar population of cells, termed lymphoid tissue inducer-like cells (LTi-like cells), supports the formation of organized gut-associated lymphoid tissue (GALT) in the intestine, including both isolated lymphoid follicles (ILFs) and cryptopatches (CPs). Both LTi and LTi-like cells require expression of the transcription factor RORgammat for their differentiation and function, and mice lacking RORgammat lack lymph nodes, Peyer's patches, and other organized GALT. In ILFs and cryptopatches, LTi-like cells are in close contact with different populations of intestinal dendritic cells (DCs), including a subpopulation recently shown to extend dendrites and sample luminal microflora. This interaction may allow for communication between the intestinal lumen and the immune cells in the lamina propria, which is necessary for maintaining homeostasis between the commensal microflora and the intestinal immune system. The potential functional implications of the organization of LTi-like cells, DCs, and lymphocytes in the lamina propria are discussed in the context of maintenance of homeostasis and of infectious diseases, particularly HIV infection.
Asunto(s)
Intestinos/inmunología , Ganglios Linfáticos/inmunología , Animales , Células Dendríticas/inmunología , Humanos , Mucosa Intestinal/inmunología , Ratones , Ratones Mutantes , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares , Ganglios Linfáticos Agregados/inmunología , Receptores de Ácido Retinoico/inmunología , Receptores de Hormona Tiroidea/inmunología , Linfocitos T/citología , Linfocitos T/inmunologíaRESUMEN
Dendritic cells (DCs) interface innate and adaptive immunity in nonlymphoid organs; however, the exact distribution and types of DC within the kidney are not known. We utilized CX3CR1GFP/+ mice to characterize the anatomy and phenotype of tissue-resident CX3CR1+ DCs within normal kidney. Laser-scanning confocal microscopy revealed an extensive, contiguous network of stellate-shaped CX3CR1+ DCs throughout the interstitial and mesangial spaces of the entire kidney. Intravital microscopy of the superficial cortex showed stationary interstitial CX3CR1+ DCs that continually probe the surrounding tissue environment through dendrite extensions. Flow cytometry of renal CX3CR1+ DCs showed significant coexpression of CD11c and F4/80, high major histocompatibility complex class II and FcR expression, and immature costimulatory but competent phagocytic ability indicative of tissue-resident, immature DCs ready to respond to environment cues. Thus, within the renal parenchyma, there exists little immunological privilege from the surveillance provided by renal CX3CR1+ DCs, a major constituent of the heterogeneous mononuclear phagocyte system populating normal kidney.
Asunto(s)
Comunicación Celular/inmunología , Células Dendríticas/citología , Riñón/citología , Riñón/inmunología , Receptores de Quimiocina/inmunología , Animales , Receptor 1 de Quimiocinas CX3C , Células Dendríticas/inmunología , Citometría de Flujo , Proteínas Fluorescentes Verdes/genética , Sistema Inmunológico/citología , Sistema Inmunológico/inmunología , Ratones , Ratones Transgénicos , Fagocitos/citología , Fagocitos/inmunología , Receptores de Quimiocina/genéticaRESUMEN
The human immunodeficiency virus has evolved various mechanisms to exploit its host cells, including the interruption and augmentation of signal transduction pathways. Recently, two DNA microarray studies have illustrated a remarkably broad-based perturbation in host transcriptional responses, which is in part mediated by the HIV-encoded Nef protein. HIV therefore seems to function as a 'master regulator' of cellular gene expression.
Asunto(s)
Regulación de la Expresión Génica/fisiología , VIH/fisiología , Linfocitos T/virología , Células Cultivadas , Productos del Gen nef/fisiología , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Transducción de Señal/fisiología , Linfocitos T/fisiología , Productos del Gen nef del Virus de la Inmunodeficiencia HumanaRESUMEN
The process of thymocyte development culminates in the maturation of helper (CD4+) and cytotoxic (CD8+) T cells from their common precursors, the CD4+CD8+ double-positive cells. A crucial step during lineage specification is the termination of expression of either the CD4 or the CD8 coreceptor. A silencer element within the first intron of the CD4 gene is sufficient for CD4 transcriptional repression in cells of the cytotoxic lineage, as well as in thymocytes at earlier stages of differentiation. Here we show that the function of the CD4 silencer is required only at distinct stages of development. Its deletion before the initiation of lineage specification resulted in CD4 derepression throughout thymocyte differentiation. By contrast, once cells committed to the cytotoxic CD8+ lineage, the CD4 locus remained silent through subsequent mitoses, even when the silencer element was excised. The epigenetic inheritance of the silenced CD4 locus was not affected by the inhibition of DNA methylation or histone deacetylation, and may thus involve other mechanisms that ensure a stable state of gene expression.
Asunto(s)
Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/metabolismo , Linaje de la Célula/genética , Citotoxicidad Inmunológica , Silenciador del Gen , Linfocitos T Citotóxicos/citología , Linfocitos T Citotóxicos/metabolismo , Animales , Linfocitos T CD4-Positivos/inmunología , Diferenciación Celular/genética , Metilación de ADN , Citometría de Flujo , Regulación de la Expresión Génica , Ratones , Ratones Transgénicos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Linfocitos T Citotóxicos/inmunología , Transcripción GenéticaRESUMEN
In a reconstituted flow chamber system, preincubation with chemokines can trigger the arrest of rolling monocytes, suggesting that this interaction could help recruit these cells to early atherosclerotic lesions. To date, however, the contribution of endothelium-derived chemokines found in these lesion to monocyte arrests has not been investigated. The endothelium of lesion-prone carotid arteries from apolipoprotein E-deficient (ApoE(-/-)) mice, but not control mice, presents the chemokines KC (mouse GRO-alpha) and JE (mouse monocyte chemoattractant protein-1 [MCP-1]). Arrest of a monocytic cell line or mouse blood monocytes perfused through carotid arteries of ApoE(-/-) mice was reduced by treating with either pertussis toxin, an antagonist of CXCR2, or an antibody to KC, but this process was insensitive to agents that blocked CCR-2 or JE. Conversely, monocyte accumulation more than doubled upon pre-perfusion of the carotid artery with KC but not with mouse MCP-1. Blockade of alpha(4)beta(1) integrin (VLA-4) or vascular cell adhesion molecule-1, but not CD18 or intercellular adhesion molecule-1, almost completely inhibited the arrest of monocytes. We conclude that when presented by early atherosclerotic lesions, KC but not murine MCP-1 triggers VLA-4-dependent monocyte recruitment.
Asunto(s)
Arteriosclerosis/metabolismo , Quimiocina CCL2/metabolismo , Quimiocina CCL2/fisiología , Quimiocinas CXC , Factores Quimiotácticos/metabolismo , Factores Quimiotácticos/fisiología , Endotelio Vascular/metabolismo , Sustancias de Crecimiento/metabolismo , Sustancias de Crecimiento/fisiología , Péptidos y Proteínas de Señalización Intercelular , Monocitos/metabolismo , Monocitos/fisiología , Animales , Anticuerpos Monoclonales/metabolismo , Antígenos CD18/metabolismo , Arterias Carótidas/metabolismo , Adhesión Celular , Línea Celular , Quimiocina CXCL1 , Humanos , Integrina alfa4beta1 , Integrinas/metabolismo , Ratones , Ratones Endogámicos C57BL , Toxina del Pertussis , Unión Proteica , Ratas , Receptores de Interleucina-8B/antagonistas & inhibidores , Receptores Mensajeros de Linfocitos/metabolismo , Factores de Tiempo , Factores de Virulencia de Bordetella/farmacologíaRESUMEN
Interstitial fluid is constantly drained into lymph nodes (LNs) via afferent lymph vessels. This conduit enables monocyte-derived macrophages and dendritic cells to access LNs from peripheral tissues. We show that during inflammation in the skin, a second recruitment pathway is evoked that recruits large numbers of blood-borne monocytes to LNs via high endothelial venules (HEVs). Inhibition of monocyte chemoattractant protein (MCP)-1 blocked this inflammation-induced monocyte homing to LNs. MCP-1 mRNA in inflamed skin was over 100-fold upregulated and paralleled MCP-1 protein levels, whereas in draining LNs MCP-1 mRNA induction was much weaker and occurred only after a pronounced rise in MCP-1 protein. Thus, MCP-1 in draining LNs was primarily derived from inflamed skin. In MCP-1(-/-) mice, intracutaneously injected MCP-1 accumulated rapidly in the draining LNs where it enhanced monocyte recruitment. Intravital microscopy showed that skin-derived MCP-1 was transported via the lymph to the luminal surface of HEVs where it triggered integrin-dependent arrest of rolling monocytes. These findings demonstrate that inflamed peripheral tissues project their local chemokine profile to HEVs in draining LNs and thereby exert "remote control" over the composition of leukocyte populations that home to these organs from the blood.
Asunto(s)
Presentación de Antígeno/inmunología , Quimiocina CCL2/inmunología , Endotelio Linfático/inmunología , Ganglios Linfáticos/inmunología , Monocitos/inmunología , Traslado Adoptivo , Animales , Antígenos/inmunología , Transporte Biológico , Quimiocina CCL2/administración & dosificación , Quimiocina CCL2/metabolismo , Quimiotaxis/inmunología , Femenino , Adyuvante de Freund , Hemocianinas/inmunología , Leucocitos Mononucleares/inmunología , Macrófagos/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Fagocitosis/inmunología , Piel/inmunologíaRESUMEN
DC-SIGN, a type II membrane protein with a C-type lectin binding domain that is highly expressed on mucosal dendritic cells (DCs) and certain macrophages in vivo, binds to ICAM-3, ICAM-2, and human and simian immunodeficiency viruses (HIV and SIV). Virus captured by DC-SIGN can be presented to T cells, resulting in efficient virus infection, perhaps representing a mechanism by which virus can be ferried via normal DC trafficking from mucosal tissues to lymphoid organs in vivo. To develop reagents needed to characterize the expression and in vivo functions of DC-SIGN, we cloned, expressed, and analyzed rhesus macaque, pigtailed macaque, and murine DC-SIGN and made a panel of monoclonal antibodies (MAbs) to human DC-SIGN. Rhesus and pigtailed macaque DC-SIGN proteins were highly similar to human DC-SIGN and bound and transmitted HIV type 1 (HIV-1), HIV-2, and SIV to receptor-positive cells. In contrast, while competent to bind virus, murine DC-SIGN did not transmit virus to receptor-positive cells under the conditions tested. Thus, mere binding of virus to a C-type lectin does not necessarily mean that transmission will occur. The murine and macaque DC-SIGN molecules all bound ICAM-3. We mapped the determinants recognized by a panel of 16 MAbs to the repeat region, the lectin binding domain, and the extreme C terminus of DC-SIGN. One MAb was specific for DC-SIGN, failing to cross-react with DC-SIGNR. Most MAbs cross-reacted with rhesus and pigtailed macaque DC-SIGN, although none recognized murine DC-SIGN. Fifteen of the MAbs recognized DC-SIGN on DCs, with MAbs to the repeat region generally reacting most strongly. We conclude that rhesus and pigtailed macaque DC-SIGN proteins are structurally and functionally similar to human DC-SIGN and that the reagents that we have developed will make it possible to study the expression and function of this molecule in vivo.
Asunto(s)
Moléculas de Adhesión Celular , Lectinas Tipo C , Lectinas/fisiología , Receptores de Superficie Celular/fisiología , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/inmunología , Mapeo Epitopo , Humanos , Lectinas/química , Lectinas/inmunología , Lectinas/metabolismo , Macaca mulatta , Macaca nemestrina , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Conejos , Receptores de Superficie Celular/química , Receptores de Superficie Celular/inmunologíaRESUMEN
Antibody-secreting plasma cells are nonrecirculatory and lodge in splenic red pulp, lymph node medullary cords, and bone marrow. The factors that regulate plasma cell localization are poorly defined. Here we demonstrate that, compared with their B cell precursors, plasma cells exhibit increased chemotactic sensitivity to the CXCR4 ligand CXCL12. At the same time, they downregulate CXCR5 and CCR7 and have reduced responsiveness to the B and T zone chemokines CXCL13, CCL19, and CCL21. We demonstrate that CXCL12 is expressed within splenic red pulp and lymph node medullary cords as well as in bone marrow. In chimeric mice reconstituted with CXCR4-deficient fetal liver cells, plasma cells are mislocalized in the spleen, found in elevated numbers in blood, and fail to accumulate normally in the bone marrow. Our findings indicate that as B cells differentiate into plasma cells they undergo a coordinated change in chemokine responsiveness that regulates their movements in secondary lymphoid organs and promotes lodgment within the bone marrow.
Asunto(s)
Quimiocinas CXC/metabolismo , Quimiocinas/metabolismo , Plasma/citología , Plasma/metabolismo , Receptores CXCR4/metabolismo , Animales , Médula Ósea/metabolismo , Movimiento Celular , Quimiocina CCL19 , Quimiocina CCL21 , Quimiocina CXCL12 , Quimiocina CXCL13 , Quimiocinas CC/metabolismo , Quimiocinas CXC/genética , Femenino , Ganglios Linfáticos/fisiología , Masculino , Ratones , Ratones Endogámicos , Ratones Mutantes , Receptores CCR7 , Receptores CXCR4/genética , Receptores CXCR5 , Receptores de Quimiocina/metabolismo , Receptores de Citocinas/metabolismo , Bazo/fisiologíaRESUMEN
Spinal interneurons help to coordinate motor behavior. During spinal cord development, distinct classes of interneurons are generated from progenitor cells located at different positions within the ventral neural tube. V0 and V1 interneurons derive from adjacent progenitor domains that are distinguished by expression of the homeodomain proteins Dbx1 and Dbx2. The spatially restricted expression of Dbx1 has a critical role in establishing the distinction in V0 and V1 neuronal fate. In Dbx1 mutant mice, neural progenitors fail to generate V0 neurons and instead give rise to interneurons that express many characteristics of V1 neurons-their transcription factor profile, neurotransmitter phenotype, migratory pattern, and aspects of their axonal trajectory. Thus, a single progenitor homeodomain transcription factor coordinates many of the differentiated properties of one class of interneurons generated in the ventral spinal cord.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas de Homeodominio/metabolismo , Interneuronas/metabolismo , Médula Espinal/metabolismo , Células Madre/metabolismo , Animales , Movimiento Celular , Embrión de Pollo , Ratones , Ratones Mutantes , Fenotipo , Médula Espinal/embriología , Médula Espinal/crecimiento & desarrollo , beta-Galactosidasa/metabolismo , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Zinc finger-containing GLI proteins are involved in the development of Caenorhabditis elegans, Xenopus, Drosophila, zebrafish, mice, and humans. In this study, we show that an isoform of human GLI-2 strongly synergizes with the Tat transactivating proteins of human immunodeficiency virus types 1 and 2 (HIV-1 and -2) and markedly stimulates viral replication. GLI-2 also synergizes with the previously described Tat cofactor cyclin T1 to stimulate Tat function. Surprisingly, GLI-2/Tat synergy is not dependent on either a typical GLI DNA binding site or an intact Tat activation response element but does require an intact TATA box. Thus, GLI-2/Tat synergy results from a mechanism of action which is novel both for a GLI protein and for a Tat cofactor. These findings link the GLI family of transcriptional and developmental regulatory proteins to Tat function and HIV replication.
Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Escherichia coli , Productos del Gen tat/genética , Productos del Gen tat/metabolismo , Proteínas de la Membrana/metabolismo , Receptores de Superficie Celular , Elementos de Respuesta , Factores de Transcripción/metabolismo , Activación Transcripcional , Animales , Línea Celular , Células Quimiorreceptoras , Ciclina T , Ciclinas/metabolismo , Proteínas de Drosophila , Infecciones por VIH/virología , VIH-1/genética , VIH-1/fisiología , VIH-2/genética , VIH-2/fisiología , Humanos , Factores de Transcripción de Tipo Kruppel , Ratones , Proteínas Nucleares , Plásmidos , Elementos de Respuesta/genética , TATA Box/fisiología , Factores de Transcripción/genética , Transfección , Replicación Viral , Proteína Gli2 con Dedos de Zinc , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
Notch proteins influence cell-fate decisions in many developing systems. Several gain-of-function studies have suggested a critical role for Notch 1 signaling in CD4-CD8 lineage commitment, maturation and survival in the thymus. However, we show here that tissue-specific inactivation of the gene encoding Notch 1 in immature (CD25+CD44-)T cell precursors does not affect subsequent thymocyte development. Neither steady-state numbers nor the rate of production of CD4+ and CD8+ mature thymocytes is perturbed in the absence of Notch 1. In addition, Notch 1-deficient thymocytes are normally sensitive to spontaneous or glucocorticoid-induced apoptosis. In contrast to earlier reports, these data formally exclude an essential role for Notch 1 in CD4-CD8 lineage commitment, maturation or survival.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Proteínas de la Membrana/fisiología , Receptores de Superficie Celular , Timo/inmunología , Factores de Transcripción , Proteínas Virales , Animales , Apoptosis/efectos de los fármacos , Antígenos CD4/genética , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD8-positivos/efectos de los fármacos , División Celular , Linaje de la Célula , Células Cultivadas , Eliminación de Gen , Marcación de Gen , Glucocorticoides/farmacología , Integrasas/genética , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptor Notch1 , Bazo/inmunología , Subgrupos de Linfocitos T/clasificación , Timo/citología , TransgenesRESUMEN
The cytoplasmic protein tyrosine kinase Tec has been proposed to have important functions in hematopoiesis and lymphocyte signal transduction. Here we show that Tec-deficient mice developed normally and had no major phenotypic alterations of the immune system. To reveal potential compensatory roles of other Tec kinases such as Bruton's tyrosine kinase (Btk), Tec/Btk double-deficient mice were generated. These mice exhibited a block at the B220(+)CD43(+) stage of B cell development and displayed a severe reduction of peripheral B cell numbers, particularly immunoglobulin (Ig)M(lo)IgD(hi) B cells. Although Tec/Btk(null) mice were able to form germinal centers, the response to T cell-dependent antigens was impaired. Thus, Tec and Btk together have an important role both during B cell development and in the generation and/or function of the peripheral B cell pool. The ability of Tec to compensate for Btk may also explain phenotypic differences in X-linked immunodeficiency (xid) mice compared with human X-linked agammaglobulinemia (XLA) patients.
Asunto(s)
Antígenos CD , Linfocitos B/inmunología , Proteínas Tirosina Quinasas/fisiología , Agammaglobulinemia Tirosina Quinasa , Animales , Linfocitos B/citología , Linfocitos B/efectos de los fármacos , División Celular , Línea Celular , Femenino , Inmunoglobulina A/sangre , Inmunoglobulina D/biosíntesis , Inmunoglobulina G/sangre , Inmunoglobulina M/biosíntesis , Inmunoglobulina M/sangre , Antígenos Comunes de Leucocito/biosíntesis , Leucosialina , Lipopolisacáridos/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mitógenos/farmacología , Mutagénesis , Fenotipo , Proteínas Tirosina Quinasas/deficiencia , Proteínas Tirosina Quinasas/genética , Recombinación Genética , Sialoglicoproteínas/biosíntesis , Bazo/citología , Linfocitos T/citología , Linfocitos T/inmunologíaRESUMEN
Chemokines play necessary and important roles in regulating the trafficking of lymphocytes to intra- or interlymphoid tissues as well as to sites of inflammation. The complex migratory patterns of lymphoid lineage cells is governed by subset-specific expression of chemokine receptors and their access to specific ligands. Several chemokine receptors and chemokine receptor-like orphan receptors also serve, in conjunction with CD4, as coreceptors for infection by human and simian immunodeficiency viruses (HIV and SIV). Here we show that the expression pattern of Bonzo/STRL33, an orphan SIV/HIV coreceptor, is highly restricted to the memory subset of T cells and is up-regulated upon stimulation of these cells with IL-2 or IL-15. Both the pattern and the regulation of Bonzo expression closely paralleled that of CC family chemokine receptors CCR5 or CCR6 and inversely correlated with CXCR4 expression. However, in striking contrast to CCR5, Bonzo expression was not down-modulated by PMA or mitogen stimulation of T cells. Targeted replacement of the Bonzo gene with a gene encoding green fluorescent protein in mice revealed that the expression and cytokine regulation of mouse Bonzo are comparable to those of its human counterpart. The similar expression and regulation patterns of Bonzo and the HIV coreceptor CCR5 may have implications for understanding the role of HIV/SIV receptors in viral evolution and pathogenesis.
Asunto(s)
Regulación de la Expresión Génica/inmunología , Lentivirus/metabolismo , Receptores CCR5/metabolismo , Receptores de Citocinas/genética , Receptores de Citocinas/metabolismo , Receptores Acoplados a Proteínas G , Receptores Virales/genética , Receptores Virales/metabolismo , Animales , Células Cultivadas , Secuencia Conservada , Citocinas/fisiología , Marcación de Gen , Marcadores Genéticos/inmunología , Vectores Genéticos/inmunología , Proteínas Fluorescentes Verdes , Humanos , Lactante , Interfase/inmunología , Lentivirus/genética , Lentivirus/inmunología , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/metabolismo , Proteínas Luminiscentes/biosíntesis , Proteínas Luminiscentes/genética , Activación de Linfocitos/inmunología , Proteínas de la Membrana/biosíntesis , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Procesamiento Proteico-Postraduccional/inmunología , Receptores CCR5/biosíntesis , Receptores CXCR6 , Receptores de Quimiocina , Receptores de Citocinas/biosíntesis , Receptores de Citocinas/inmunología , Receptores Virales/biosíntesis , Receptores Virales/inmunología , Eliminación de Secuencia , Linfocitos T/inmunología , Linfocitos T/metabolismoRESUMEN
Most developing thymocytes undergo apoptosis because they cannot interact productively with molecules encoded by the major histocompatibility complex. Here, we show that mice lacking the orphan nuclear hormone receptor RORgamma lose thymic expression of the anti-apoptotic factor Bcl-xL. RORgamma thus regulates the survival of CD4+8+ thymocytes and may control the temporal window during which thymocytes can undergo positive selection. RORgamma was also required for development of lymph nodes and Peyer's patches, but not splenic follicles. In its absence, there was loss of a population of CD3-CD4+CD45+ cells that normally express RORgamma and that are likely early progenitors of lymphoid organs. Hence, RORgamma has critical functions in T cell repertoire selection and lymphoid organogenesis.
Asunto(s)
Quinasas CDC2-CDC28 , Tejido Linfoide/crecimiento & desarrollo , Receptores Citoplasmáticos y Nucleares/fisiología , Receptores de Ácido Retinoico , Receptores de Hormona Tiroidea , Proteínas Represoras , Subgrupos de Linfocitos T/citología , Timo/citología , Factores de Transcripción , Animales , Apoptosis , Recuento de Células , Ciclo Celular , Supervivencia Celular , Cruzamientos Genéticos , Quinasa 2 Dependiente de la Ciclina , Quinasas Ciclina-Dependientes/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Femenino , Marcación de Gen , Proteína 2 Inhibidora de la Diferenciación , Tejido Linfoide/citología , Tejido Linfoide/embriología , Masculino , Ratones , Ratones Endogámicos C57BL , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Proteína bcl-XRESUMEN
The seven-transmembrane receptor CX(3)CR1 is a specific receptor for the novel CX(3)C chemokine fractalkine (FKN) (neurotactin). In vitro data suggest that membrane anchoring of FKN, and the existence of a shed, soluble FKN isoform allow for both adhesive and chemoattractive properties. Expression on activated endothelium and neurons defines FKN as a potential target for therapeutic intervention in inflammatory conditions, particularly central nervous system diseases. To investigate the physiological function of CX(3)CR1-FKN interactions, we generated a mouse strain in which the CX(3)CR1 gene was replaced by a green fluorescent protein (GFP) reporter gene. In addition to the creation of a mutant CX(3)CR1 locus, this approach enabled us to assign murine CX(3)CR1 expression to monocytes, subsets of NK and dendritic cells, and the brain microglia. Analysis of CX(3)CR1-deficient mice indicates that CX(3)CR1 is the only murine FKN receptor. Yet, defying anticipated FKN functions, absence of CX(3)CR1 interferes neither with monocyte extravasation in a peritonitis model nor with DC migration and differentiation in response to microbial antigens or contact sensitizers. Furthermore, a prominent response of CX(3)CR1-deficient microglia to peripheral nerve injury indicates unimpaired neuronal-glial cross talk in the absence of CX(3)CR1.
Asunto(s)
Receptores de Citocinas/fisiología , Receptores del VIH/fisiología , Animales , Receptor 1 de Quimiocinas CX3C , Expresión Génica , Marcación de Gen , Genes Reporteros , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Ratones , Ratones Mutantes , Mutagénesis Insercional , Fenotipo , Receptores de Citocinas/genética , Receptores del VIH/genéticaRESUMEN
Stimulation of beta-adrenergic receptor normally results in signaling by the heterotrimeric G protein G(s), leading to the activation of adenylyl cyclase, production of cAMP, and activation of cAMP-dependent protein kinase (PKA). Here we report that cell death of thymocytes can be induced after stimulation of beta-adrenergic receptor, or by addition of exogenous cAMP. Apoptotic cell death in both cases was observed with the appearance of terminal deoxynucleotidyl transferase-mediated UTP end labeling reactivity and the activation of caspase-3 in S49 T cells. Using thymocytes deficient in either Galpha(s) or PKA, we find that engagement of beta-adrenergic receptors initiated a Galpha(s)-dependent, PKA-independent pathway leading to apoptosis. This alternative pathway involves Src family tyrosine kinase Lck. Furthermore, we show that Lck protein kinase activity can be directly stimulated by purified Galpha(s). Our data reveal a new signaling pathway for Galpha(s), distinct from the classical PKA pathway, that accounts for the apoptotic action of beta-adrenergic receptors.
Asunto(s)
Apoptosis , Proteínas de Unión al GTP/metabolismo , Receptores Adrenérgicos beta/metabolismo , Transducción de Señal , Animales , Apoptosis/efectos de los fármacos , Supervivencia Celular , AMP Cíclico/farmacología , Proteínas Quinasas Dependientes de AMP Cíclico/deficiencia , Proteínas Quinasas Dependientes de AMP Cíclico/genética , Citometría de Flujo , Proteínas de Unión al GTP/genética , Etiquetado Corte-Fin in Situ , Isoproterenol/farmacología , Proteína Tirosina Quinasa p56(lck) Específica de Linfocito/metabolismo , Linfoma/metabolismo , Ratones , Mutación , Linfocitos T/metabolismo , Células Tumorales CultivadasRESUMEN
Productive interaction of a T lymphocyte with an antigen-presenting cell results in the clustering of the T-cell antigen receptor (TCR) and the recruitment of a large signalling complex to the site of cell-cell contact. Subsequent signal transduction resulting in cytokine gene expression requires the activation of one or more of the multiple isoenzymes of serine/threonine-specific protein kinase C (PKC). Among the several PKC isoenzymes expressed in T cells, PKC-theta is unique in being rapidly recruited to the site of TCR clustering. Here we show that PKC-theta is essential for TCR-mediated T-cell activation, but is dispensable during TCR-dependent thymocyte development. TCR-initiated NF-kappaB activation was absent from PKC-theta(-/-) mature T lymphocytes, but was intact in thymocytes. Activation of NF-kappaB by tumour-necrosis factor alpha and interleukin-1 was unaffected in the mutant mice. Although studies in T-cell lines had suggested that PKC-theta regulates activation of the JNK signalling pathway, induction of JNK was normal in T cells from mutant mice. These results indicate that PKC-theta functions in a unique pathway that links the TCR signalling complex to the activation of NF-kappaB in mature T lymphocytes.
Asunto(s)
Isoenzimas/metabolismo , Activación de Linfocitos , FN-kappa B/fisiología , Proteína Quinasa C/metabolismo , Receptores de Antígenos de Linfocitos T/fisiología , Linfocitos T/inmunología , Animales , Antígenos CD/metabolismo , Femenino , Hemocianinas/inmunología , Humanos , Isoenzimas/genética , Leucopoyesis , Masculino , Ratones , Mutagénesis , Proteína Quinasa C/genética , Proteína Quinasa C-theta , Transducción de Señal , Linfocitos T/enzimología , Timo/citologíaRESUMEN
Dendritic cells (DC) capture microorganisms that enter peripheral mucosal tissues and then migrate to secondary lymphoid organs, where they present these in antigenic form to resting T cells and thus initiate adaptive immune responses. Here, we describe the properties of a DC-specific C-type lectin, DC-SIGN, that is highly expressed on DC present in mucosal tissues and binds to the HIV-1 envelope glycoprotein gp120. DC-SIGN does not function as a receptor for viral entry into DC but instead promotes efficient infection in trans of cells that express CD4 and chemokine receptors. We propose that DC-SIGN efficiently captures HIV-1 in the periphery and facilitates its transport to secondary lymphoid organs rich in T cells, to enhance infection in trans of these target cells.
Asunto(s)
Linfocitos T CD4-Positivos/virología , Células Dendríticas/fisiología , Proteína gp120 de Envoltorio del VIH/metabolismo , Infecciones por VIH/transmisión , VIH-1/fisiología , Membrana Mucosa/virología , Receptores del VIH/fisiología , Antígenos CD4/fisiología , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Moléculas de Adhesión Celular/fisiología , Movimiento Celular , Células Cultivadas , Cuello del Útero/citología , Técnicas de Cocultivo , Células Dendríticas/inmunología , Células Dendríticas/virología , Femenino , Humanos , Lectinas/fisiología , Ganglios Linfáticos/citología , Ganglios Linfáticos/inmunología , Ganglios Linfáticos/virología , Tejido Linfoide/citología , Tejido Linfoide/virología , Sustancias Macromoleculares , Masculino , Membrana Mucosa/citología , Receptores CCR5/fisiología , Recto/citología , Transfección , Útero/citologíaRESUMEN
Naive Itk-deficient CD4+ T cells were unable to establish stable IL-4 production, even when primed in Th2-inducing conditions. In contrast, IFNgamma production was little affected. Failure to express IL-4 occurred even among cells that had gone through multiple cell divisions and was associated with a delay in the kinetics and magnitude of NFATc nuclear localization. IL-4 production was restored genetically by retroviral reconstitution of Itk or biochemically by augmenting the calcium flux with ionomycin. In vivo, Itk-deficient mice were unable to establish functional Th2 cells. Development of protective Th1 cells was unimpeded. These data define a nonredundant role for Itk in modulating signals from the TCR/CD28 pathways that are specific for the establishment of stable IL-4 but not IFNgamma expression.